1. Field of the Invention
The present invention relates generally to ladders and, more particularly, is concerned with a leveling apparatus for adjusting the lengths of opposite side rails of a ladder to compensate for the unevenness of the surface upon which the ladder is placed so that the ladder can be maintained in a substantially level, upright position.
2. Description of the Prior Art
Oftentimes it is necessary to use a ladder in locations where the ground on which to support the ladder is uneven or sloping. The user will usually have to dig a shallow hole in order to level the ladder; otherwise, a dangerous lateral tilt is imparted to the ladder which ordinarily renders it unsafe to use. However, on some surfaces, such as roofs, steps and sloping sidewalks, such leveling measures cannot be applied.
Over the years, various ladder leveling devices have been proposed in the prior art to compensate for surface incline and unevenness. Representative of the prior art are the devices disclosed in U.S. Pat. Nos. to Hoit (2,330,825), Biery (2,366,829), Derby et al (2,890,824), Sturdy et al (3,173,512), McCarty (3,258,085), Zevely (3,260,329), Sturm (3,794,141) and Wilson (4,497,390). While many of these devices would appear to operate reasonably well and generally achieve their objectives under the range of operating conditions for which they were designed, most seem to embody shortcomings which make them less than an optimum ladder leveling device. Some leveling devices are complicated and expensive to manufacture, while other devices are awkward to use and not completely reliable in operation.
Consequently, a need still exists for a ladder leveling mechanism which is self-adjusting, easy to use, simple in construction and operation, and reliable.